Improved Adaptive Controller Synthesis of Piecewise‐Affine Systems

This paper considers the adaptive control problem for piecewise affine systems (PWS), a novel synthesis framework is presented based on the piecewise quadratic Lyapunov function (PQLF) instead of the common quadratic Lyapunov function to achieve the less conservatism. First, by designing the projection‐type piecewise adaptive law, the problem of the adaptive control of PWS can be reduced to the control problem of augmented piecewise systems. Then, we construct the piecewise affine control law for augmented piecewise systems in such a way that the PQLF can be employed to establish the stability and performance. In particular, the Reciprocal Projection Lemma is employed to formulate the synthesis condition as linear matrix inequalities (LMIs), which enables the proposed PQLF approach to be numerically solvable. Finally, an engineering example is shown to illustrate the synthesis results.     

Analyses and improvement of a broadcasting multiple blind signature scheme based on quantum GHZ entanglement

A broadcasting multiple blind signature scheme based on quantum GHZ entanglement has been presented recently. It is said that the scheme’s unconditional security is guaranteed by adopting quantum key preparation, quantum encryption algorithm and quantum entanglement. In this paper, we prove that each signatory can get the signed message just by an intercept–resend attack. Then, we show there still exist some participant attacks and external attacks. Specifically, we verify the message sender Alice can impersonate each signatory to sign the message at will, and so is the signature collector Charlie. Also, we demonstrate that the receiver Bob can forge the signature successfully, and with respect to the external attacks, the eavesdropper Eve can modify the signature at random. Besides, we discover Eve can change the signed message at random, and Eve can impersonate Alice as the message sender without being discovered. In particular, we propose an improved scheme based on the original one and show that it is secure against not only the attacks mentioned above but also some collusion attacks.     

An uncertainty-based approach to discrete-time fault estimation observer design for nonuniformly sampled systems

This paper considers the fault estimation problem of nonuniformly sampled system in which sensor sampling is performed at aperiodic interval. After being discretized at sampling instant, the nonuniformly sampled system is modeled as an equivalent polytopic system with norm bounded uncertainties. A discrete-time time-varying fault estimation observer with multiple design freedom is then constructed, and a sufficient condition given in linear matrix inequality (LMI) is provided to obtain the constant filter gain and ensure not only the asymptotic stability of fault estimation error but also the robustness of uncertainties. Compared with the existing observer designed based on continuous-time delay approach, the proposed one has a better estimation accuracy and less conservatism and is easy for digital implementation. A numerical simulation and a quadruple-tank benchmark are used to demonstrate the effectiveness and superiority of the proposed method.     

On design optimization for structural crashworthiness and its state of the art

Optimization for structural crashworthiness and energy absorption has become an important topic of research attributable to its proven benefits to public safety and social economy. This paper provides a comprehensive review of the important studies on design optimization for structural crashworthiness and energy absorption. First, the design criteria used in crashworthiness and energy absorption are reviewed and the surrogate modeling to evaluate these criteria is discussed. Second, multiobjective optimization, optimization under uncertainties and topology optimization are reviewed from concepts, algorithms to applications in relation to crashworthiness. Third, the crashworthy structures are summarized, from generically novel structural configurations to industrial applications. Finally, some conclusions and recommendations are provided to enable academia and industry to become more aware of the available capabilities and recent developments in design optimization for structural crashworthiness and energy absorption.

     

基于CMYK空间的火灾区域粒子群优化快速定位方法

将CMYK彩色模型下的火焰颜色特征与粒子群优化(Particle swarm optimization,PSO)算法求最优适应度函数相结合,通过合理配置检测窗口邻域中颜色的M,y各低阶矩的特征在欧氏距离分类适应度函数中的因子及PSO中各参数,使森林监测图像的可疑火灾着火点的初定位控制在0.05s以内,最后通过对火灾样本关键图与初定位可疑着火点的颜色互信息的计算而得到进一步的校验和确定.实验表明改进的PSO算法具有良好的火焰区域定位效果及运算效率,易于移植到前端探测的嵌入式火灾探测系统.     

Importance sampling for volumetric illumination of flames

Physically based rendering of scenes with volumetric illumination of flames remains a challenging problem due to the complexity of their heterogeneous radiative properties. Current bidirectional importance sampling strategies have been focusing on emissive light sources without anisotropic extinction. In this paper, we present an efficient importance sampling method for volumetric light sources with anisotropic extinction. According to the radiative properties of flames, we separate the computation of anisotropic extinction from the evaluation of illumination inside flames and utilize cluster-based hierarchies to rapidly estimate them. To exploit the coherence of radiative voxels, we also propose a new similarity metric to aggregate voxels into clusters. For each pixel to be shaded, we use these clusters to rapidly approximate the importance function of voxels, and draw final illumination samples from clusters. Our results show that this approach substantially reduces the variance of images when rendering scenes with flames.     

RMPCT技术在连续重整装置上的应用

催化连续重整是石油加工中极其重要的工艺过程。由于反应复杂,过程变量多,变量之间耦合严重,存在许多重要不易测量变量,使过程控制难度大,采用常规的PID单回路控制有很大的局限性。多变量模型预估控制MPC是石油化工生产中广泛应用的1种先进控制策略。霍尼韦尔公司在MPC的基础上开发出了鲁棒多变量模型预测控制技术RMPCT。将R...     

离心压缩机自动控制系统的设计和应用

介绍以ＰＣ－ＢＵＳ工控机为中心构成离心压缩机自动控制系统的设计及在化工生产中的应用,实践证明,该系统工作可靠,经济效益显著,达到了设计目的。     

一种快速模板匹配目标识别算法

该文拟将计算机视觉中传统模板匹配方法与对场景物体的中心矩描述方法相结合,提出了一种效率较高的匹配算法。算法在匹配识别上不仅不受物体方位旋转及尺寸缩放变化影响,而且能较精确地求出物体相对于模板的缩放比例和偏转角度。文中给出了与传统模板匹配算法对照的实验结果。     

一种基于PC机的高速16位并行数据采集接口

介绍了一种在PC机上实现的高速16位并行数据采集接口。该接口由高速光电隔离电路,双端口FIFO存储缓冲器电路及由FPGA芯片构成的计算机接口逻辑与控制电路等组成。该接口电路将终端显示处理系统与前端数据处理系统通过光电耦合器隔离开来,避免了它们之间的相互干扰,较好地解决了16位并行数据高速传输中存在的电磁干扰问题和大数据量实时有效传输问题。采用现场可编码门阵列FPGA芯片,使硬件设计软件化,既实现了复杂逻辑功能设计,又减少了硬件电路规模,提高了系统的可靠性,在雷达、声纳等复杂系统中具有良好的应用价值。